The structure model of the conical twin screw extruder is very different from other ordinary screw extruders and has a unique structure.In recent years, it has played a great role in the processing industry. Three conical twin?screw extruders with the ratio of the groove depth to the screw radius of 1∶2, 2∶5, and 1∶3 were designed.The process of extruding LDPE and HDPE particles from the conical twin?screw extruder was simulated by the discrete element method, and the particle velocity change in the groove of the conical twin?screw extruder was analyzed. At the same time,the conveying efficiency of the three types of conical twin screw extruders were compared under different parameters. The discrete element analysis of LDPE and HDPE particles was carried out using EDEM software, and the mixing situation of the two kinds of particles in the three conical twin?screw extruders at different times was obtained.The results show that the mixing efficiency of the conical twin?screw extruder with the ratio of screw groove depth to screw radius of 1∶2 is better than that of the conical twin?screw extruder with the ratio of the groove depth to the screw radius of 2∶5 and 1∶3.